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Battery Pack becomes slightly out of balance overnight?

Discussion in 'Roadster: Technical' started by sethr, Aug 7, 2015.

  1. sethr

    sethr CPO Roadster #1089

    Joined:
    Mar 24, 2013
    Messages:
    152
    Location:
    Fairfax, VA
    Hi all: I wonder if anyone can shed light on what I have noticed recently (I've never checked this before the last couple of days). After a Standard charge at the end of the day, my pack balances in a short time, usually in about 10 - 15 minutes. But recently, when I was checking on the pack temperature in the morning, I saw that the balancing grid had a few "1's". It rebalanced in minutes (I assume because I had woken the Roadster up: the pump had not been on), but I'm wondering if this is normal, or the beginning of a problem? TIA!
     
  2. spaceballs

    spaceballs Member

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    Sep 17, 2013
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    538
    Location:
    Sammamish
    That is normal.
     
  3. BartJ

    BartJ Member

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    Dec 13, 2014
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    Location:
    Belgium
    Personally I have never seen any 1's in the balancing grid at all
     
  4. djp

    djp Roadster 2.0 VIN939

    Joined:
    Aug 28, 2011
    Messages:
    1,108
    Location:
    Toronto, Canada
    You need to catch them during a balancing cycle, directly after completing a Standard or Range charge. They're cleared out when you start the car.
     
  5. hcsharp

    hcsharp Active Member

    Joined:
    Jun 7, 2011
    Messages:
    2,537
    Location:
    Vermont
    I've never seen my car "re-balance" after it finishes balancing. Maybe I've missed it. If you top-off the charge it will enter a balancing stage afterwards. But I've never seen it start balancing just because it woke up.
     
  6. MLAUTO

    MLAUTO Member

    Joined:
    Mar 8, 2014
    Messages:
    315
    Location:
    SW Florida
    Check the min and max brick voltages. Balancing will start after a few minutes after the key is turned off (or when you awaken it) when the SOC is 79% or greater, and the difference between the high and low voltages is >.02V. Balancing only occurs while awake. If your pack is out of balance, you can turn on the hazard flashers to keep the car awake until the pack is balanced. A few "1's" are good. If you see 98, then you have a problem.
     

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